The invention relates to a variable compression piston assembly, and to an engine that has double ended pistons connected to a universal joint for converting linear motion of the pistons to rotary motion.
Most piston driven engines have pistons that are attached to offset portions of a crankshaft such that as the pistons are moved in a reciprocal direction transverse to the axis of the crankshaft, the crankshaft will rotate.
U.S. Pat. No. 5,535,709, defines an engine with a double ended piston that is attached to a crankshaft with an off set portion. A lever attached between the piston and the crankshaft is restrained in a fulcrum regulator to provide the rotating motion to the crankshaft.
U.S. Pat. No. 4,011,842, defines a four cylinder piston engine that utilizes two double ended pistons connected to a T-shaped T-shaped connecting member that causes a crankshaft to rotate. The T-shaped connecting member is attached at each of the T-cross arm to a double ended piston. A centrally located point on the T-cross arm is rotatably attached to a fixed point, and the bottom of the T is rotatably attached to a crank pin which is connected to the crankshaft by a crankthrow which includes a counter weight.
In each of the above examples, double ended pistons are used that drive a crankshaft that has an axis transverse to the axis of the pistons.
According to the invention, a variable compression piston assembly includes a plurality of pistons, a transition arm coupled to each of the pistons, and a rotating member coupled to a drive member of the transition arm and mounted for pivoting movement to slide along an axis of the drive member. Movement of the rotating member relative to the drive member changes the compression ratio of the piston assembly.
Embodiments of this aspect of the invention may include one or more of the following features.
The pistons are double ended pistons. The transition arm is coupled to each of the double ended pistons at approximately a center of each double ended piston. There are two pistons and the axis of rotation of the rotating member and axes of the two pistons lie on a common plane.
In certain illustrated embodiments, the rotating member is a flywheel. A counterweight is mounted to the rotating member. The rotating member is pivotably mounted to a main drive shaft. The axis of the main drive shaft is parallel to the axis of each of the pistons.
A movable pressure plate is in contact with a peripheral region of the rotating member. A roller interfaces the pressure plate and the rotating member. A piston biases the rotating member into contact with the pressure plate.
The drive member extends into an opening in the rotatable member adjacent to a periphery of the rotatable member. The drive arm extends into a pivot pin located in the rotatable member. A universal joint connects the transition arm to a support.
According to another aspect of the invention, a method for varying the compression ratio of a piston assembly includes providing a plurality of pistons, a transition arm coupled to each of the pistons, and a rotating member coupled to a drive member of the transition arm and mounted for pivoting movement to slide along an axis of the drive member. The method includes pivoting the rotating member to change the compression ratio of the piston assembly.
According to another aspect of the invention, a method of increasing the efficiency of a piston assembly includes providing a plurality of double ended pistons, a transition arm coupled to each of the double ended pistons at approximately a center of each of the pistons, and a rotating member coupled to a drive member of the transition arm and mounted for pivoting movement to slide along an axis of the drive member. The method includes pivoting the rotating member to change the compression ratio of the double ended piston assembly.
According to another aspect of the invention, a joint for positioning between first and second elements arranged for linear motion along a common axis includes an outer member and an inner member. The outer member is configured for movement relative to the first and second elements along a first axis perpendicular to the common axis. The inner member is mounted within the outer member for rotation relative to the outer member about a second axis perpendicular to the first axis and the common axis. The outer and inner members each define an opening for receiving a drive arm.
Embodiments of this aspect of the invention may include one or more of the following features.
The outer member is configured for movement relative to the first and second elements along the second axis. The outer member defines first and second parallel flat sides each defining a plane perpendicular to the common axis. First and second sliding members are positioned between the first flat side and the first element and the second flat side and the second element, respectively. The flat sides have a polished surface.
The first and second elements are pistons. Alternatively, the first element is a piston and the second element is a guided rod, e.g., of a compressor.
The drive arm defines a longitudinal axis and the joint includes a mount, e.g., a cap screw, for holding the drive arm axially stationary while permitting the drive arm to rotate about its longitudinal axis.
In an illustrated embodiment, the opening in the inner member for receiving the drive arm is a channel defining a channel axis perpendicular to the second axis. The opening in the outer member for receiving the drive arm is a slot for accommodating movement of the drive arm when the inner member rotates relative to outer member.
A thrust bearing receives an axial load transferred to the drive arm by the first and second elements. A sleeve bearing receives a normal load transferred to the drive arm by the first and second elements. There is also a bearing located between the inner and outer members.
The first and second elements are mounted to a connector and the connector defines a cavity within which the outer and inner members are positioned.
According to another aspect of the invention, a piston assembly includes first and second elements configured for linear motion along a common axis and a joint positioned between the first and second elements. At least one of the first and second elements is a piston.
According to another aspect of the invention, a method of reducing side load in a double ended member having first and second elements arranged for linear motion along an axis of the double ended member includes providing a joint located between the first and second elements, and transferring load between the first and second elements and a drive arm mounted to the joint through two opposed surfaces, e.g., flat surfaces, of an outer member of the joint.
According to another aspect of the invention, an engine assembly includes a first piston assembly including at least two engine pistons coupled by a transition arm, and a second piston assembly coupled to the first piston assembly. The second piston assembly including at least two engine pistons coupled by a transition arm. The first and second piston assemblies are mounted back-to-back and 180xc2x0 out of phase.
Embodiments of this aspect of the invention may include one or more of the following features. The engine pistons are housed in cylinders with pairs of engine pistons from the first and second piston assemblies sharing a common cylinder. Each piston assembly includes compressor pistons mounted to move with respective engine pistons. Each piston assembly includes six pistons and two compressors.
In an illustrated embodiment, a first rotating member is mounted to the transition arm of the first piston assembly, and a second rotating member is mounted to the transition arm of the second piston assembly. The second rotating member is coupled to the first rotating member.
According to another aspect of the invention, a method of cancelling vibration in an engine assembly includes providing a first piston assembly including at least two engine pistons coupled by a transition arm, providing a second piston assembly including at least two engine pistons coupled by a transition arm, and coupling the first and second piston assemblies in a back-to-back relationship and 180xc2x0 out of phase.